On the regularity of the pressure field of Brenier's weak solutions to incompressible Euler equations

In this paper we improve the regularity in time of the gradient of the pressure field arising in Brenier's variational weak solutions (Comm Pure Appl Math 52:411-452, 1999) to incompressible Euler equations. This improvement is necessary to obtain that the pressure field is not only a measure, but a function in L-loc(2) ((0, T); BVloc(D)). In turn, this is a fundamental ingredient in the analysis made by Ambrosio and Figalli ( 2007, preprint) of the necessary and sufficient optimality conditions for the variational problem by Brenier (J Am Mat Soc 2:225-255, 1989; Comm Pure Appl Math 52:411-452, 1999).